Automatic switching system



Oct. 28, 1952 w. H. cUTTlNo 2,615,962

AUTOMATIC SWITCHING SYSTEM Filed July 22, 1950 ATTOR ,i Y

Patented Oct. 28, 1952 AUTOMATIC SWITCHING SYSTEM William H.' Cuttine, Wilkinsburg, Pa., assigner to Westinghouse Electric` Corporation, East Pittsburgh, Pa.,a,corporationA of Pennsylvania Applieaton July 22, 1950, Serial' No. ,17 55,367

6 Claims,

My invention relates, generally, to switching systems, and it has' reference, in particular, to automatic' switching systems, suehas may be used to control the cennectionscf capacitors, orthe like, to a power system;

Generally stated, it is anobject ofmy invention to provide a switching system for capacitors that-issimple and inexpensive to manufacture, and isV reliable and effective in operation.

More specifically, it is an object ofmy in vent-ion to provide, in a switching system for capacitors, ier using a contactor'device for conu rolling the connections of the capacitors to apower circuit and using fuses to provide the necessary fault protection.

Another' object ofv my invention is to provide, ina capacitor switching system, for using a con'-V tactor with a latch type control relay which must be reset after the contacter is closed te set up a closing circuit for subsequently reclosing the contacter, so as te prevent reclosing inthe event' the contacter opens due tor a loss of" voltage- It is an important object of my invention to provide, in a switching'system for capacitors, for preventing pumping ofv an oil switch contaeter used for controlling the connections of the capacitorsY to a power circuit.

Yet another object of my invention is to provide, in a capacitorV switching system, for utilining a simple oil switch contacter and a volt-l age responsive' Control panel for controlling the connection of the capacitor to a power circuit.

t is an important object of my invention te provide a simple and inexpensive control system for controlling the operation of a contacter device connecting capacitorsv to a power circuit.

Other objects will in part be obvious, and'will in part be explained hereinafter.r

In practicing my invention according to one of its embodiments, an oil switch contacter is utilized te effect connection of capacitors te a power circuit in response to operation of avoltage relay connected to the power circuit. A latch type control relay is used to provide an operating circuit for a. closing relay and complete the operating circuit for the contacter, and is operated each time the contacter closes, so that it must be reset in order te subsequently reclose the con',- tactor. The voltage relay resets the control re lay a predetermined time after the voltage of the circuit has dropped below a predetermined value, so that the control relay prevents reclosing of the contacter in the event that it opens due to a loss of voltage as a result of a capacitor fault.

For a more complete understanding of the nature and scope of my invention, reference may be made to the following detailed description, which may be read in connection with the accompanying drawing, in whichv the single figure is a diagrammatic view ofv a capacitor switching system, embodyingv the. invention in one` of; its

bank, te the-conductors I3 through IBf of a powercircuit, whichmaybe connected to! a suitable sourceet' alternating: current.

The capacitors lil mayv be connected' to the conductors I3, I4' and l5` by means of an. eil switch contacter L82 havingan operating winding i3 which must/be energized tod effect operation ofthe switch,- andfwhi'ch must bemaintained. in.

energized'- eondition te. manitain the switch closed A closing. relay 2l]L havingY an' operatingwinding- 22 may be utilized: teVv connect the operiating winding i9" of the'. switch i8` to a suitable source ofecen-trol voltage, whichniay be supplied freina controlV transformer- 24 connected to the conductors l5V and H5.A

Gperation ofthe closing` relay-ilJniayy be effected by means o-ia closing` time delay relay 2c 25 under the control of a voltage relay 2B, whichA mayy he energized from the control transformer 24, seA astev operate andA engage stationary contactmembers 28a or- 28h, to raiseand" lot'verfV positionsV in response to decreasesI and'I increases- 30 oi voltage in the circuit.- hetime delayrelay :,361 may, for example, be of the thermal leimetalv type, comprising a heater element 26uv disposedA to; bej connected to the-,source 4by. theY velt-age relay i3; and a bimetallic contact member 2615 disposed tev be; actuated into" engagement wit-h a' l, stationary contact member 26ev for effectingk energzatien ofj' the operatingv Winding 22- of' the closing relay 20. y

n Order to prevent repeated reQIQSineL or 4o pumpingy of theY contacterswitch, I. ngthe eventik tliratity opens due tov af, losser voltage" resulting, for' example, from; a, fam-tf en; @naar the @apa-citer units,beforev theuprimary fuse l2 for the particu, larbank can clear the circuit, a control relay 30' having an operatingr Winding 3|,jrnay be utilized: The control relay 3l) may be disposed to corriplete the4 energizing circuit for' the operating Winding i9, Off thev sw'thl llV and'. interrupt the' energizing., circuit; of, the closing relay 2G; se as tov 5o Dre-,vent reclosire of the breaker. The. operating.

Winding 311 may;V f'r example. te1 energized through Contact.'v 'in'peinler 2,027- ofij the closing re-Y The. Control relayV 3D1 may'. be orfl the',

lay 2li, latch type, being; for example, providedv with a;

latch mechanism z2A fjq'ri leaning. the relay in the operating position,

A. reset winding 32almayf be provided in cen. junction with` the latch.v mechanism` 32 for. re.,- leasmg the latch` mechanism to restore the con-4 trol relay te a normaler non-operated. position.

Reset ofthe Control, relay 30 be normally the.. reference eiected by connecting the reset winding 32a to the control source ,through a trip time delay relay 35 which may be of the thermal bimetallic device comprising a heater element 35a and a bimetallic contact member 35h disposed to normally engage a stationary contact member 35C and operable to engage a normally opened contact member 35d.

In order to provide selective control of the contactor switch i8, a control switch 38 may be provided which may be selectively operable to an automatic position for connecting the operating winding 22 of the closing relay and the reset winding 32a of the latch mechanism for energization under the control of the voltage relay 28, or to a manual position for eiecting direct connection of the winding of the closing relay 20 to the control source.

With the system in the deenergized position as shown, the control switch 38 may be operated to the right, to the automatic position, and the control switch 25 may be closed to connect the control circuits to the control transformer 24. If the voltage relayy 28 happens to be operated to the right-hand or raise operating position in response to a reduction of the voltage of the power circuit, an obvious energizing circuit will be provided for the heater 26a, of the closing time delay relay 26 through contact members 28a and 30h. After a predetermined interval of time, contact member 26h engages contact member 26e, and an energizing circuit is provided for the operating winding 22 of the closing relay 20, extending from the left-hand control conductor t@ through conductor lli, operating winding 22, conductor 32, contact member 3de of the control relay 36, conductor llt, contact member 25e, contact member 2th, conductor 45, contact member 38e, and conductor it to the left-hand control conductor lll.

The closing relay 2B thereupon operates, setting up an energizing circuit for the operating winding I9 of the switch i8 through contact member 20a, and providing a holding circuit for itself through contact member 2Go and normally closed contact members 35o and 35D of the trip time delay relay 35. At the same time an obvious energizing circuit is provided for the operating winding 3l of the control relay 3o through contact member 20h. The control relay 3o operates. and the latch mechanismv 32 latches it in the operated position. The energizing circuit for the heater 26a of the closing time delay relay 2S is interrupted at contact member 30D so as to prevent continuous energization of the heating element in the event the contactor i8 should open without the control relay 3@ being reset, which condition may occur in the event of a loss of voltage.

Operation of the control relay 30 to the energized position also interrupts the initial energizing circuit for the operating winding 22 of the closing relay 2o at contact member 33e. Thus, should the contactor `I8 open due to a loss of voltage or a collapse ofvoltage due to a fault, which condition may readily occur before failure of one of the capacitor units comprising one of the banks li operates the primary line fuse I2 of the bank, the closing'relay 22 cannot be reclosed even though the bimetallic contact member 2Gb of the closing time delay relay 26 remains in Contact with the stationary contact member 26e for a predetermined time. The control relay 30 must be reset to complete the energizing circuit for the operating winding 22 of the closing relay 2U at contact member 3c.

Reset of the control relay 30 can only be effected through energization of the reset winding 32a as a result of operation of the trip time delay relay 35 in response to operation of the voltage relay 23 to the left-hand or lower operating position. This condition will not be attained when there is a loss of voltage caused by closing on a fault, since the loss of voltage will not be of suicient duration, and when the contactor switch I8 opens, the closing relay 20 is deenergized at the same time and must remain deenergized as its energizing circuit is interrupted at contact member Bile, since the control relay 30 remains latched in the operated position.

Should the voltage of the power system exceed the predetermined value for which the voltage relay 223 is calibrated, while the capacitors are connected to the power circuit, an obvious energizing circuit is provided for the heater element 35a, and after a predetermined interval of time contact member 35h engages the stationary contact member 35d, providing an obvious energizing circuit for the reset winding 32a, of the latch mechanism and interrupting the holding circuit of the closing relay 2o at contact member 35o. The control relay .-iii is released. and is restored to its normal or non-operated position, interrupting the energizing circuit for the operating winding I9 of the contactor Hi at contact member 3fm. Contact member 3th closes to set up an energizing circuit for the heater 26a of the closing time delay relay 26. Contact member 30o sets up the energizing circuit for the operating winding 22 of the closing relay 2U, so that the system is reset for retaking the capacitors i2 to the power circuit in response to subsequent operation of the voltage relay 2B.

Manual operation of the contactor switch I8 may be effected by operating the control switch 38 to the left-hand or manual position and then moving it to either the close or trip position to set up obvious energizing circuits for the operating winding 22 of the closing relay 20 and the trip winding 32a of the latch mechanism 32 through contact members 38a, and 38d, or 3327 and 38e, respectively.

From the above description and accompanying drawing, it will be found that I have provided a simple and inexpensive switching system for switching small capacitors where the fault protection is provided by means of main or primary fuses for each bank of capacitor units which are usually of such capacity that a fault on a single section or unit of one of the capacitor banks will usually result in opening of the contactor due to loss of voltage, particularly where the capacitors are at the end of a long line, before the primary fuse operates to clear the iault. By utilizing a latch type control relay which must be reset in response to operation of the voltage relay before the contactor may be reclosed, repetitive closing of the contactor on a fault may be prevented. A control system embodying the features of my invention comprises a minimum amount of equipment and a minimumof expense. It is, therefore, highly adaptable to numerous capacitor installations which have heretofore been permanently connected and which 4it is desired to change over to an automatic switching system.

Since certain changes may be made in the above-described construction, and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all the matter contained in the above description and shown in the accompanying drawing shall be considered illustrative and not in a limiting sense.

I claim as my invention:

1. The combination with a contactor type switch operable to connect a load device to a power circuit, of a voltage relay responsive to the voltage of the circuit, means including a control relay operable to complete an operating circuit for the switch, means releasably retaining the control relay in the operating position, a closing relay, circuit means including contacts of the closing relay connected to set up said operating circuit for said switch and eiect operation of the control relay to complete said operating circuit, and a circuit including a movable contact operable in accordance with the voltage responsive relay and a normally closed contact of the control relay connected to effect operation of the closing relay.

2. The combination with a switch device having an operating winding disposed to be energized to maintain the switch closed and connect an electrical device to a power circuit, of means including a closing relay connected to set up an energizing circuit for said operating winding, a control relay, an operating circuit for the closing relay including a normally closed contact of the control relay, said control relay having a contact connected in series with the operating winding of the switch operable to an operating position in response to operation of the closing relay to complete the operating circuit for the switch, a latch releasably retaining the control relay in the operating position, and means including a relay operable in response to the voltage of the power circuit to complete the operating circuit for the closing relay.

3. In a switching system, a switch device having an operating winding to eiect operation of the switch device to connect an electrical device to a power circuit, a closing relay having contact means connected in series circuit with said winding to set up an energizing circuit for said operating winding, means including a control relay of the latch type operable in response to operation of the closing relay to complete the energizing circuit for the operating winding o1" the switch device, said control relay having a latch releasably retaining it in the operated position and having normally closed contacts which open when the control relay so operates, a circuit including contact means actuated in response to a reduction in the voltage of the power circuit and said normally closed contact means connected to provide an operating circuit for the closing relay,

and an additional circuit including a contact actuated in response to an increase in the voltage of the power circuit connected to provide a reset circuit for effecting operation of said releasable latch to release the control relay from the operated position.

4. A switching system comprising, a switch device operable to make a connection to a power circuit, said switch device having an operating winding, means including a closing relay operable to set up an energizing circuit for the switch device and provide a holding circuit for itself, a control relay of the latched-in operating position type, a, circuit including contacts of the control relay connected to complete said energizing circuit, said control relay having a reset winding disposed to release the relay to a normal nonoperated position when energized, a voltage relay responsive to the voltage of the power circuit, a circuit including time delay means operable in response to operation of the voltage relay when the voltage increases above a predetermined value to connect the reset winding for energization, another circuit including additional time delay means operable in response to a reduction in the voltage below a predetermined value to connect an operating circuit for the closing relay, and normally closed contact means of the control relay connected in series with said operating circuit to render the additional time delay means ineffective unless the control relay is reset.

5. A switching system comprising, a switch device having an operating winding disposed to be energized to close the device and hold it closed to make a connection to a power circuit, means including a closing relay operable to set up an energizing circuit for said operating winding, a control relay of the latch type having an operating winding and a reset winding, a circuit connecting the operating Winding of the control relay to be energized to eiect operation of the closing relay to complete said energizing circuit, another circuit connecting the said reset winding disposed to be energized to reset 4the control relay to a a non-operated position, means including a voltage control relay operable in response to voltage conditions of the power circuit to selectively energize the closing relay and the reset winding, and means including a manual switch selectively operable to diierent positions to set up energizing circuits for the closing relay and the reset winding either directly or through the voltage control means.

6. In a switching system, a switch having an l operating winding disposed when energized to close the switch and make a connection to a power circuit, means including a closing relay operable to set up an energizing circuit for the operating winding, circuit means including a control relay operable in response to operation of the closing relay to complete the energizing circuit for said operating winding, said control relay being of the latched-in-operating position type and having a reset winding disposed when energized to release it to a normal position, a voltage relay having a contact member actuated in response to the voltage of the power circuit, time delay closing and tripping relays, circuits connecting said time delay relays to be selectively responsive to operation of the voltage relay, a circuit including a normally closed contact of the control relay connected in series circuit relation with the time delay closing means to render it inoperative except when the control relay is reset, another circuit including a contact operable in response to operation of the time delay tripping means connected to energize the reset winding of the control relay, and an additional circuit including a normally closed contact of the control relay connected in circuit relation with contact means of the time delay closing means and the closing relay to prevent reclosing the switch unless the control relay is reset.

WILLIAM H. CUTTINO.

REFERENCES CITED The following references are of record in the rile of this patent:

UNITED STATES PATENTS Number Name Date 1,780,664 Anderson Nov. 4, 1930 1,780,676 Hough Nov. 4, 1930 2,388,639 Marbury Nov. 6', 1945 

